I don't believe this is possible. If you're looking for more than the standard Xbox visualization you may need to pick up the Xbox Music Mixer. Unless you already have a modded Xbox, then the sky's the limit.

"The computer had attained consciousness, only to reject it, claiming it was too unstable an operating system."

Here's a little trick I found out about if you want some sort of visuals while playing music. While playing a song, quickly press Y then X. The small visuals from the jewel will blow up to full screen size. Exit by hitting any button. You can also hit the 'info' button on the DVD remote and the same thing happens.